<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
    <style>
        .box{
            width: 30px;
            height: 30px;
            border:100px solid red;

            border-right-color: blue;
            border-top-color: yellow;
            border-bottom-color: pink;
        }

        .box2{
            width: 100px;
            height: 100px;
            border: 50px solid red;
            border-right: none;

            border-bottom-right-radius: 10px;
        }
    </style>
</head>
<body>
    <div class="box"></div>

    <div class="box2"></div>
</body>
</html>